Genetic, biochemical, and biophysical analysis of the metabolic regulatoy enzyme, L-threonine deaminase from Salmonella typhimurium is being studied in order to describe the mechanism whereby small molecular weight compounds medulate enzyme activity. An amibivalent role of this enzyme in genetic regulation of the ilv gene cluster will be studied by using genetic analysis and by in vitro analysis of gene expression. BIBLIOGRAPHIC REFERENCES: Decedue, C.J., Hofler, J.G., & Burns, R.O. Threonine Deaminase from Salmonella typhimurium Relationship Between Regulatory Sites. J. Biol. Chem. 250: 1963 (1975). Hofler, J.G., Decedue, C.J., Luginbuhl, G.H., Reynolds, J.A. and Burns, R.O. The subunit structure of alpha-Acetohydroxyacid Isomeroreductase from Salmonella typhimurium. J. Biol. Chem. 250: 277 (1975).